Rare earth magnet.
An example of the element Neodymium

Rare earth magnet.
Neodymium magnets are very brittle and are therefore often plated with nickel. Ed Pegg demagnetized one of his magnets (to protect any laptop computers put on the table over the element), and I chipped away some of the plating. We think this is probably about 30% neodymium.
These are dangerously strong magnets! In fact they are so strong you can levitate bits of pyrolytic graphiteover them, as you can see in the video.Source:Force FieldContributor:Ed Pegg JrAcquired:15 April, 2002Price: $3Size: 0.5"Purity: <35%